1. Field
Embodiments of this invention relate to a touch screen panel.
2. Related Art
In recent years, along with the development of the electronics industry, display devices, such as a liquid crystal display, an electroluminescent display, and a plasma display panel having a quick response speed, low power consumption, and an excellent color reproduction rate, have been in the spotlight. The display device is used for various electronic products such as televisions, monitors for computers, notebook computers, mobile telephones, display units for refrigerators, personal digital assistants, automated teller machines, and the like. In general, the display device interfaces with various input devices such as a keyboard, a mouse, and a digitizer. However, when a separate input device such as a keyboard, a mouse, or digitizer is used, a user is required to know how to use the separate input device, and as the separate input device occupies space, customer dissatisfaction is increased. Therefore, there is increasingly a need for a convenient and simple input device that can reduce erroneous operation. Also, there is a need for a touch screen panel in which a user can input information by directly contacting a screen with a finger or a pen.
Since the touch screen panel has a simple configuration, which minimizes erroneous operations, the user can perform an input action without a separate input device, and can quickly and easily manipulate through contents displayed on a screen.
Touch screen panels are classified into a resistive type, a capacitive type, an electromagnetic type according to a detection method of a touched portion. The resistive type touch screen panel determines a touched position by a voltage gradient according to a change of resistance in a state where a DC voltage is applied to metal electrodes formed on an upper plate or a lower plate. The capacitive type touch screen panel senses a touched position according to a difference in capacitance created in an upper or lower plate when the user physically contacts with a conductive film formed on the upper or lower plate. The electromagnetic type touch screen panel detects a touched portion by reading an LC value induced as an electromagnetic pen touches a conductive film.
Hereinafter, a capacitive type touch screen panel in the related art will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view illustrating a capacitive type touch screen panel in the related art, and FIG. 2 is a sectional view taken along the lines I-I′, II-II′ and III-III′ in the touch screen panel shown in FIG. 1.
Referring to FIGS. 1 and 2, the capacitive type touch screen panel in the related art includes an electrode forming part 20, a routing wire forming part 40, a pad forming part 60, and a protective layer 50.
The electrode forming part 20 is formed on a substrate 10 and includes a plurality of first electrodes 21 arranged in parallel in a first direction (for example, an X-axis direction) and a plurality of second electrodes 22 arranged to intersect in a direction (for example, a Y-axis direction) perpendicular to the first electrodes 21. The first electrodes 21 and the second electrodes 22 intersect each other, but sustain an electrical insulation state by an insulation layer 30. Further, neighboring first electrodes 21 arranged in the first direction are connected to each other by a bridge 41. That is, the bridge 41 connects the neighboring first electrodes 21 to each other through contact holes 30a and 30b formed in the insulation layer 30 covering the first and second electrodes 21 and 22.
The routing wire forming part 40 is formed on the substrate 10 at positions outside the electrode forming part 20 and includes a plurality of first routing wires 42 connected to the plurality of first electrodes 21, respectively, and a plurality of second routing wires 43 connected to the plurality of second electrodes 22, respectively.
The pad forming part 60 includes a plurality of first pads 61 connected to the plurality of first electrodes 21 through the plurality of first routing wires 42, respectively, and a plurality of second pads 62 connected to the plurality of second electrodes 22 through the plurality of second routing wires 43, respectively.
The protective layer 50 covers the electrode forming part 20 and the routing wire forming part 40 and prevents the first and second electrodes 21 and 22 and the first and second routing wires 42 and 43 from being exposed to the outside environment.
Hereinafter, a method of manufacturing a capacitive type touch screen panel in the related art will be described with reference to FIGS. 3A to 3D.
Referring to FIG. 3A, a first conductive layer for forming first and second electrodes is entirely deposited on the substrate 10 including three parts corresponding to an electrode forming part 20, a routing wire forming part 40, and the pad forming part 60 through a deposition process such as a sputtering method. As the first conductive layer, an indium tin oxide (ITO) layer is generally used. After a photoresist is coated on the substrate 10 on which the first conductive layer is formed, a first photoresist pattern for exposing the first conductive layer is formed in the electrode forming part 20 by performing a photolithography process using a first photomask. After removing the first conductive layer exposed by the first photoresist pattern through wet etching, a plurality of first electrodes 21 and a plurality of second electrodes 22 intersecting the first electrodes 21 are formed on the substrate 10 by ashing the remaining first photoresist pattern.
In FIG. 3B, the first insulation layer 30 is formed on a portion of the substrate 10 on which the plurality of first and second electrodes 21 and 22 are formed, then the first insulation layer 30 on the pad forming part 60 and the routing wire forming part 40 is removed and first and second contact holes 30a and 30b penetrating the first insulation layer 30 on the electrode 21 are formed through a photolithography process and an etching process using a second photomask. The first and second contact holes 30a and 30b expose a portion of the neighboring first electrodes 21. The first insulation layer 30 includes silicon nitride, silicon oxide, or organic resin.
Referring to FIG. 3C, a second conductive layer is formed on an entire surface of the substrate 10 on which the first and second contact holes 30a and 30b are formed through a deposition process such as a sputtering method. The second conductive layer includes aluminum (Al) or molybdenum (Mo). After coating a photoresist on the substrate on which the second conductive layer is formed, first and second routing wires 42 and 43 are formed in a routing wire forming part on the substrate 10, a connection electrode 41 is formed on the first insulation layer 30 of the electrode forming part 20, and first pads 61 and second pads 62 are formed in a pad forming part on the substrate 10 by performing a photolithography process and an etching process using a third photomask. The connection electrode connects the neighboring first electrodes 21 to each other through the first and second contact holes 30a and 30b formed in the first insulation layer 30.
In FIG. 3D, a second insulation layer 50 as a protective film is formed on an entire surface of the substrate 10 on which the connection electrode 41 and the first and second routing wires 42 and 43 are formed, then through holes 50a, 50b and 50c for penetrating the second insulation layer 50 is formed to expose the first and second pads 61 and 62 with a photolithography process and an etching process using a fourth photomask.
However, the capacitive type touch screen panel in the related art is manufactured using four—photomask processes, as described above, and each photomask process accompanies a photolithography process requiring a series of continuous processes, such as photoresist (PR) coating, photomask alignment, PR exposure, PR development, and PR cleaning, and thus it is necessary to reduce the number of photomask processes in terms of time and costs.